datamap.js

function initMap() {
   var map = new google.maps.Map(document.getElementById('map'), {
   zoom: 12,
   mapTypeId:google.maps.MapTypeId.HYBRID,
   scrollwheel: true,
   center: { lat: 41.876, lng: -87.624 }
 });

   var georssLayer = new google.maps.KmlLayer({
        url: 'datamap.kml'
   });
   georssLayer.setMap(map);

function addMarker(feature) {
    var marker = new google.maps.Marker({
    position: feature.position,
    label: {text: feature.title, color: "yellow"},
    animation:google.maps.Animation.BOUNCE,
    map: map
    });
}

function addOption(feature, i) {
    var name = 'marker ' + i;
    var option = '<option value="'+ i +'">' + name + '</option>';
    document.getElementById('dropdown').innerHTML += option;
}

function selectOpion(selectElm) {
    var i = Number(selectElm.value);
    map.setCenter(features[i].position);
    map.setZoom(13);
  }
  google.maps.event.addDomListener(document.getElementById('dropdown'), 'change', function(e) {
    selectOpion(this);
  });
  var features = [{
    position: new google.maps.LatLng(1.5252265, 101.7205939),
    title: 'Place Name 0',
  }, {
    position: new google.maps.LatLng(-0.4938175, 101.47658145000001),
    title: 'Place Name 1',
  }, {
    position: new google.maps.LatLng(0.32034099999999993, 101.06136349999998),
    title: 'Place Name 2',
  }, {
    position: new google.maps.LatLng(1.68450545, 101.4448306),
    title: 'Place Name 3',
  }, {
    position: new google.maps.LatLng(0.5137912, 101.441176),
    title: 'Place Name 4',
  }, {
    position: new google.maps.LatLng(-0.49255899999999997, 102.24846645),
    title: 'Place Name 5',
  }, {
    position: new google.maps.LatLng(-0.293274, 103.18415300000001),
    title: 'Place Name 6',
  }, {
    position: new google.maps.LatLng(0.16251709999999997, 102.43564895),
    title: 'Place Name 7',
  }, {
    position: new google.maps.LatLng(2.0708884499999995, 100.80535549999999),
    title: 'Place Name 8',
  }, {
    position: new google.maps.LatLng(0.8932599499999999, 100.49054645),
    title: 'Place Name 9',
  }, {
    position: new google.maps.LatLng(0.828033, 101.90484455),
    title: 'Place Name 10',
  }];
    for (var i = 0, feature; feature = features[i]; i++) {
    addMarker(feature);
    addOption(feature, i);
    }
}